1. Field of the Invention
The present invention relates to a process for the treatment of industrial waste water by electrolysis and, more particularly, for cleaning industrial waste water recovered, for example, from industrial boilers, or otherwise containing contaminants, utilizing an electrocoagulative process to chemically bond with a particle to change the particle from in solution to in suspension which can be flocculated and separated from the water. The invention also relates to an apparatus for carrying out the process and especially to an electrolytic cell sludge thickener bubble pump and clarifier used for that purpose.
2. Description of the Related Art
The present invention is directed to improving processes and apparatuses for removing impurities from fluids in a manner which is safe, economical, and user friendly. Attempts by others to provide improvements in the art of water purification are represented by the inventions described below.
U.S. Pat. No. 3,849,281 issued to Bennett, et al. discloses a vertically disposed electrolytic cell used to produce hypochlorite solutions. This unit, while impressing a sinuous path upon the fluid to be treated, requires the use of U-shaped plates as a cathode; current is applied only at the outer extremities of the device. This device is divided up into a series of partitioned cell units; it is not constructed so that the individual cell units may be easily cleaned or repaired.
U.S. Pat. No. 4,124,480 issued to Stevenson is directed to a bipolar cell consisting of stacked electrode plates which impresses a sinuous, or partially-sinuous, path upon the electrolytic fluid traveling through it. A partially sinuous path is described when fluid flow stagnation at the ends of the plates is relieved by pathways existing at the ends of certain plates along the path. This cell is used for the electrolytic generation of chlorine from sea water or other brines. The outer plates are both connected to a positive source so as to act as anodes, and the central plate is connected to a negative source to act as a cathode. This device is used for a different purpose than that of the present invention, and is not constructed so as to be particularly easy to disassemble for repair and replacement of interior parts, since each electrode is held in place with a separate O-ring type seal, which must be carefully removed from the cell assembly during inspection to avoid damage, and if damaged, requires replacement.
U. S. Pat. No. 4,339,324 issued to Haas speaks to a gas generator composed of an electrolytic cell which makes use of a series current path and parallel fluid path. Neither the function, nor the structure of this unit is similar to the present invention.
U.S. Pat. Nos. 4,406,768 and 4,500,403 issued to King, disclose other electrochemical cell assemblies; in these units the electrodes do not span the entire width of the inner chamber. However, these units do make use of a series current and parallel fluid paths.
U.S. Pat. No. 5,549,812 issued to Witt, discloses a method of electrolysis which requires a pulsed current flow and sinuous fluid path. A pulsed current source is used to break down and chemically alter contaminants in order to form a flocculate within the fluid to be treated. After treatment, the flocculate is settled in a tank for removal from the fluid. However, the cell is constructed so as to be particularly difficult to disassemble for inspection and repair. Also, the fluid path moves in different directions across each plate within the cell.
U.S. Pat. No. 3,964,991 issued to Sullins, describes an apparatus for electrolytic flocculation (i.e. electrocoagulation) of suspended colloidal particles. This device is cylindrical in form, makes use of a single, centrally-disposed electrode for operation, and is very difficult to disassemble for cleaning after extended use.
German Patent Document DE 3641365C2 is an apparatus for the cleaning and treatment of contaminated water using xe2x80x9celectroflotation,xe2x80x9d a process where iron and aluminum plates, configured as sets of cascaded electrodes, are consumed by electrolysis as waste water passes over them. This electrolytic process (termed herein as xe2x80x9celectrocoagulationxe2x80x9d) can achieve flotation over a wide pH range without the addition of chemicals, resulting in clarification or cleaning of the water. During electroflotation, metals are oxidized in the waste water to form precipitates, emulsions are broken, and oil components are converted to foam. In practice, fine gas bubbles are produced in the waste water (an electrolyte) by electrolytic action between the electrodes, which form anodes and cathodes. Liberated oxygen serves to oxidize substances in the waste water. The release of metallic ions into the waste water provides flocculating agents which cause contaminants to fall to the bottom while gas bubbles may produce a foam bed at the top. A clean water phase forms between the upper foam bed and the heavier dirty component at the bottom of the fluid bed. In this particular apparatus, both iron and aluminum (which is more expensive than iron) are used as sacrificial electrode materials.
As illustrated by the background art, efforts are continuously being made to develop improved devices for removing impurities from fluids. No prior effort, however, provides the benefits attendant with the present invention. That is, the process and apparatus according to the present invention substantially depart from conventional concepts and designs of the prior art, and in so doing, provide a means of causing particulate impurities within a fluid to cluster together to form larger particles for filtering by subsequent mechanical processes in an economical manner; provides a cell for electrocoagulation which obviates the need for numerous sealing gaskets, is easy to disassemble and clean, employs readily available parts and materials, is easily manufactured, and uses a minimum number of functional components; and includes a clarifier which is more effective than prior art clarifiers. Additionally, prior patents and commercial techniques do not suggest the present inventive combination of component elements arranged and configured as disclosed and claimed herein.
It is an object of the present invention to provide for an electrocoagulation system to more efficiently remove contaminants from waste water.
It is a further object of the present invention to provide electrocoagulation reactor cell which uses rectangular plates that are easily manufactured and which plates are easy to remove.
It is a further object of the present invention to provide electrocoagulation cell which has plates that are easy to manufacture, maintain, and remove, which also allows for the series flow of waste water therethrough.
It is a further object of the present invention to provide for electrocoagulation cell which contains multiple electrolytic cells therein such that the reactor can operate even if one cell is not functioning.
It is a further object of the present invention to provide for a vessel upstream of a clarifier that will allow sludge to settle out and thicken, which sludge will be removed from the bottom therefrom to oppress.
It is a further object of the present invention to provide for a sludge thickener in fluid communication with the clarifier of the system to cycle sludge from the clarifier back to the sludge thickener to provide more efficient operation.
It is a further object of the present invention to provide for an efficient, inexpensive low cost pump for moving waste water from one vessel to another in the system.
The present invention relates to a process for the treatment of industrial waste water by utilizing an electrocoagulative process to chemically bond with a molecule/particle in solution to change the molecule/particle from xe2x80x9cin solutionxe2x80x9d to xe2x80x9cin suspensionxe2x80x9d so the molecule can be flocculated and separated from the water as a contaminant, which may include heavy metals, dyes, oils, fats, solvents, salts, etc. The electrocoagulative process for treating industrial waste water comprises the steps of:
(a) passing low-pressure industrial waste water containing contaminants susceptible to flocculation and precipitation upon electrolysis of the waste water between electrodes of an electrocoagulation cell designed for long useful life and easy maintenance;
(b) subjecting waste water within the cell to electrolysis by energizing the electrodes with direct current, thereby breaking down and chemically altering contaminants to change the contaminants from in solution to in suspension in the electrolyzed water to form a sedimentable flocculate therein; and
(c) separating the flocculate from the resulting cleaned water, using chemical flocculent additives (if needed) and a mechanical clarifier constructed to operate more effectively with greater ease of maintenance than that required by conventional clarifiers.
The invention also anticipates an apparatus for treating waste water which comprises: a pump for moving waste water through an electrocoagulation reactor cell; the cell itself; a defoam tank to reduce the amount of bubbles present in clarified water; a clarifier having a floc mix chamber, a series of horizontally disposed slotted plates of varying lengths designed to follow a shallow inlet and steep outlet wall path, terminating in an outlet weir; and a recessed plate filter press to consolidate flocculated waste materials for disposal.
The electrocoagulation reactor cell of the present invention has ferrous electrode plates physically disposed so as to be parallel to one another, with a spacing fixed by holding slots which traverse the left and right cell walls. In other designs, the plates would also be aluminum, carbon, or of other materials depending on the waste being treated. The cell plates form a meandering guide path for waste water as it moves from the cell inlet to the cell outlet. All other fluid paths are sealed by mechanical abutting contact with a liquid sealant such as silicone being used between abutting surfaces of the outer walls of the reactor cell. Power to the cell is connected to every eleventh plate, by way of slots and holes cut into the plates with fluid-tight seals around the power links to every eleventh plate. The plates to which voltage is connected may be varied according to the design parameters of the particular system.
The clarifier of the present invention has three major containment areas for waste water which has undergone electrocoagulation: a floc mix chamber, the clarifier main body, and an outlet weir. The floc mix chamber has a baffle at the bottom to remove entrained air (passed on to the top of the clarifier) and ensure more thorough mixing of the liquid which passes through it.
The main body of the clarifier comprises a series of horizontally disposed slotted plates of varying lengths; each plate is of such a length that it follows the shallow inlet and steep outlet paths delineated by the clarifier bottom walls, which lead from the clarifier inlet, and to the clarifier outlet, respectively. The slots in the plates are of variable size, and provide a means of selecting a more or less turbulent flow along the fluid path.
Clarified liquid passes through the slots on to the outlet weir. Solids, which fall to the bottom of the clarifier main body, are drained by the operator and passed on to a filter press, where they are consolidated and taken to an appropriate disposal location.
The more important features of the invention have thus been rather broadly outlined in order that the detailed description that follows may be better understood, and the present contribution to the art better appreciated. There are, of course, additional features of the invention that will be described hereinafter forming the subject matter of the claims appended hereto. It should be appreciated by those skilled in the art that the disclosed specific methods and structures may be readily utilized as a basis for modifying or designing other methods and structures for carrying out the same purposes of the present invention. Such equivalent methods and structures do not depart from the spirit and scope of the invention as set forth in the appended claims.
It is to be understood that the invention is not limited in its application to the details of construction and arrangement of the components set forth in the following descriptive drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. In this same spirit, the phraseology and terminology employed herein should not be regarded as limiting.
Therefore, it is an object of the present invention to provide a new electrocoagulation process and apparatus which can be realized in a relatively small floor surface area.
It is another object of the present invention to provide a new electrocoagulation process and apparatus which may be easily and efficiently manufactured and marketed, being fabricated from readily available materials.
It is a further object of the present invention to provide a new electrocoagulation process and apparatus which is of a durable and reliable construction.
Yet another object of the present invention is to provide a new electrocoagulation process and apparatus which consumes a relatively small amount of power.
Still yet another object of the present invention is to provide a new electrocoagulation process and apparatus that requires minimal maintenance over its entire useful life.
It is also an object of the present invention to provide a new fluid reactor cell for causing particulate impurities within a fluid to cluster together to form larger particles which may be more easily separated by subsequent conventional mechanical processes.
It is another object of the present invention to provide a new fluid reactor cell which may be easily and efficiently manufactured and marketed, being made from readily available materials.
It is a further object of the present invention to provide a new fluid reactor cell which is of a durable and reliable construction.
Yet another object of the present invention is to provide a new fluid reactor cell which consumes a relatively small amount of power.
It is another object of the present invention to provide a new fluid reactor cell which operates effectively under relatively low-pressure and low-velocity fluid flow conditions.
Still yet another object of the present invention is to provide a new fluid reactor cell that requires only minimal maintenance over its entire useful life, i.e. the cell operates for a relatively long time before any disassembly and cleaning is necessary.
It is another object of the present invention to provide a new wastewater clarifier which may be easily and efficiently manufactured and marketed, being made from readily available materials.
It is a further object of the present invention to provide a new wastewater clarifier which is of a durable and reliable construction, the plates of the clarifier may be individually removed while the system is running.
Yet another object of the present invention is to provide a new wastewater clarifier which consumes no electrical power.
Still yet another object of the present invention is to provide a new wastewater clarifier that requires only minimal maintenance over its entire useful life.
A still further object of the present invention is to provide a new wastewater clarifier that allows operator selection of turbulence along the fluid flow path from the clarifier inlet to the clarifier outlet.
It is an object of the present invention to provide a new wastewater clarifier having a baffled flocculent mixing chamber which acts to more thoroughly mix partially-cleaned liquid with added flocculent chemicals, while simultaneously removing entrained air from the liquid.
It is another object of the present invention to provide a new wastewater clarifier with a gently-sloped entry fluid path, and a steeply-sloped exit fluid path, each serving to more efficiently separate flocculated materials from the partially-cleaned fluid.
It is a further object of the present invention to provide a new wastewater clarifier which has a multiplicity of operator selectable drain hole locations.